Synthesis of phthalideisoquinolines from 3-halophthamdes and 3,4-dihydroisoquinolinium salts

Abstract

Phthalideisoquinoline alkaloids have been synthesized by coupling appropriately substituted 3-halophthalides and 2-methyl-3,4-dihydroisoquinolinium salts in the presence of Zn(Cu) couple or metallic Zn. Both erythro and threo isomers are formed in the reaction. The nmr spectra of the (±)-erythro- and (±)-threo-isocordrastines have been reinvestigated. The results, which differ from those previously reported, lead to a different conclusion regarding the conformation of the molecules.